Gas circuit breaker insulating tube support and high pressure vessel

ABSTRACT

A two-pressure dead tank high voltage circuit breaker contains a plurality of series-connected circuit interrupters mounted within a grounded tank filled with sulfur hexafluoride at relatively low pressure. The interrupters are supported from the bottom of the tank by hollow insulation support tubes which are terminated with a blast valve assembly which in turn supports the interrupters. The insulation tubes serve the function of a pressure vessel to store relatively high pressure gas to eliminate the need for a separate pressure vessel and as a support for the blast valve assembly and also provide the necessary insulation between the interrupters and ground.

United States Patent n 1 Guaglione et a1.

GAS CIRCUIT BREAKER INSULATING TUBE SUPPORT AND HIGH PRESSURE VESSELInventors: Giovanni Paolo Guaglione, Irvine;

James R. McCloud, Burbank, both of Calif.; Hansruedi Aumayer,l-larleysville, Pa.

Assignee: I-T-E Imperial Corporation, Spring House, Pa.

Filed: Sept. 19, 1973 Appl. No.: 398,858

US. Cl. 200/148 B; 220/145 R; 200/148 R Int. Cl. H0lh 33/42 Field ofSearch 200/148 R, 148 B, 148 J,

200/148 BV, 145 R References Cited UNITED STATES PATENTS 8/1961 Smith eta1. 200/148 B June 10, 1975 McKeough 200/148 R Golota 200/148 BV [57]ABSTRACT A two-pressure dead tank high voltage circuit breaker containsa plurality of series-connected circuit interrupters mounted within agrounded tank filled with sulfur hexafluoride at relatively lowpressure. The interrupters are supported from the bottom of the tank byhollow insulation support tubes which are terminated with a blast valveassembly which in turn supports the interrupters. The insulation tubesserve the function of a pressure vessel to store relatively highpressure gas to eliminate the need for a separate pressure vessel and asa support for the blast valve assembly and also provide the necessaryinsulation between the interrupters and ground.

10 Claims, 2 Drawing Figures v a la 52 i 3 g a l .l f 1 I l I J72 eee-Hi 5/ l J04 J00 r J C 503 24 u 57 25 .4

22 7a a 0'4 a! Y I) r: /Z a n GAS CIRCUIT BREAKER INSULATING TUBESUPPORT AND HIGH PRESSURE VESSEL RELATED APPLICATIONS This applicationis related to copending application Ser. Nos. 398,871 filed Sept. l9,I973, entitled CONTACT STRUCTURE FOR HIGH VOLTAGE GAS BLAST CIRCUITINTERRUPTER, in the name of H. Aumayer; 398,870, filed Sept. 19, 1973entitled CONTACT FOR HIGH VOLTAGE GAS BLAST CIR- CUIT BREAKER WITHTIME-DELAYED OPEN- ING, in the name of L. J. Kucharski; 398,869, filedSept. 19, I973, entitled MECHANICAL SUPPORT OF TRANSIENT RECOVERYVOLTAGE CAPACI- TOR WITHIN CIRCUIT BREAKER LOW PRES- SURE TANK, in thename of L. D. McConnell, all of which are assigned to the assignee ofthe present invention.

BACKGROUND OF THE INVENTION This invention relates to high voltage gascircuit breakers, and more specifically relates to a novel insulationtube for supporting circuit interrupters within a low pressure groundedtank, which tube also serves as the major high pressure reservoir for atwo-pressure circuit breaker.

Two pressure sulfur hexafluoride circuit breakers of the dead tankvariety are well known to those skilled in the art and are shown, forexample, in U.S. Pat. No. 3,526,734, issued Sept. 1, I970, entitled DEADTANK GAS BLAST CIRCUIT BREAKER WITH INTER RUPTER STRUCTURE IMMERSED INLOW PRES- SURE OF DEAD TANK, in the name of D. H. McKeough, and assignedto the assignee of the present invention.

In the prior art type breaker, a hollow insulation column of porcelainmounted on a plate in the bottom of the flattened circular housingsupports a conductive pressure vessel of relatively large volume, whichconductive vessel serves as the main high pressure reservoir for thetwo-pressure breaker. A blast valve assembly is then mounted on thepressure vessel with a part of the blast valve being inside the pressurevessel. Two interrupting breaker assemblies are then mounted on eachblast valve assembly. High pressure gas is then supplied through thehollow porcelain insulator column to the conductive pressure vessel,where the high pressure gas is stored for breaker operation.

Upon the operation of the circuit breaker, the blast valve opens for ashort time, admitting some of the stored gas from the high pressurevessel to the interrupters. The pressure in the main vessel is thenreplenished by gas flowing through the hollow insulator column.

BRIEF SUMMARY OF THE INVENTION In accordance with the present invention,the interrupter units are supported within the low pressure groundedtank by a novel insulating support tube which may be of fiber glassreinforced with epoxy and with metal end flanges. The insulation supporttube has a relatively large diameter, for example, about 16 inches sothat it can store a relatively large amount of high pressure gas at apressure of about l5 atmospheres to serve as the main high pressurereservoir for the twopressure breaker operation. The same tube is thenused as the main support for the blast valve and its associatedinterrupters and also serves to support these members which are atrelatively high potential with respect to the grounded tank. This noveldesign then eliminates the need for a separate expensive pressure vesselmounted atop an expensive hollow porcelain column.

As a further feature of the invention, the blast valve structureassociated with each insulation support column is mounted on a top metalflange of the support tube with the valve intake being inside the tubeto provide an unrestricted flow of gas from the interior tube volume tothe valve. After each operation of the blast valve, the pressure in thesupport tube will be replenished through an appropriate opening in ametal bottom flange of the tube without any further restriction.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an elevational view of acircuit breaker which employs the novel contacts of the presentinvention where a portion of the grounded support tank of the circuitbreaker has been removed to expose the various components therein.

FIG. 2 is a cross-sectional view through one of the interrupters of thecircuit breaker of FIG. 1 and illustrates the novel contact structure ofthe present invention.

DETAILED DESCRIPTION OF THE DRAWINGS Referring first to FIG. 1, there isshown, in partial section, one phase of a high voltage circuit breakerwhich incorporates the present invention, as will be later described.The circuit breaker of FIG. 1 can, for example, be rated at 230,000volts and at 63,000 amperes. Conventionally, the breaker will be athreephase breaker and two other and identical phases to the one shownin FIG. 1 will also be provided.

In general, the circuit breaker phase of FIG. 1 is contained within agenerally flattened spherical metallic tank 10 which is supported onmetallic frame angle members 11 and 12. Angles 11 and 12 are suitablyreinforced and extend rearwardly and support additional tanks to tank10, which are spaced from the tank 10 and disposed generally parallel totank 10 and constitute the other phases of the circuit breaker. Themetallic tank 10 is a grounded housing and the circuit breaker shownherein for purposes of illustrating the invention is shown in a deadtank" configuration.

The terminal bushings for the breaker may be of any standard type andare shown for illustration herein as including the bushings l3 and 14which extend through cylindrical shrouds l5 and 16, respectively, whichare appropriately welded or otherwise secured to the tank 10 and aresealed relative to the interior of the tank. Gas barriers l7 and 18,respectively, are provided to prevent the leakage of gas from tank 10.Thus, tank 10 is filled with sulfur hexafluoride gas (or a gas mixturewhich includes sulfur hexafluoride) at a pressure of about 3atmospheres. For purposes of the invention, any dielectric gas at anyappropriate pressure could be used. For the embodiment described herein,the gas pressure within tank 10 will be designated a relatively lowpressure.

Each of the bushings 13 and I4 is further associated with currenttransformers l9 and 20, respectively, which may also be of any desiredconstruction.

A grounded flat support platform 21 is contained within the tank 10 andis supported from the bottom of tank 10 by welded support members, suchas bolts 22 and 23 and others not shown. Platform 21 sits on levelingnuts, such as nuts 24 and 25, respectively, of the support bolts. Theplatform 21 then serves as a level mount for the circuit interrupterequipment to be contained within tank 10. In the case of the breakershown in FIG. 1, four interrupters are to be connected in series withone another to define the circuit breaker voltage rating of 230 KV.Platform 21 supports two spaced hollow tubular insulation supportmembers 26 and 27, respectively, which further serve the purpose of highpressure gas reservoirs.

Each of the insulation support members 26 and 27 support, at their tops,respective blast valve housings 28 and 29 which, in turn, supportseries-connected interrupter units 30-31 and 32-33, respectively. Eachof the interrupter units contains a pair of interrupter contacts whichare simultaneously opened in the presence of a blast of gas whichassists in extinguishing the arc. It is to be noted that the tubes 26and 27, blast valve housings 28 and 29, and interrupters 30 to 33 aremechanically supported solely from the platform 21 and that none ofthese components are supported from the bushings 13 and 14 orintermediate supports for the interrupters 31 and 32.

The top of interrupter 30 is electrically connected to the stud 35 ofterminal bushing 13 through a flexible connection, which will be laterdescribed. The connection between the top of interrupter 30 and stud 35is then covered by a corona shield 36.

The bottom of interrupter 30 is then connected through housing 28 to thebottom of interrupter 31. The top of interrupter 31 is connected throughflexible shunts 36 to the top interrupter 32 with the tops ofinterrupters 31 and 32 and flexible connectors covered by corona shields37 and 38, respectively.

The bottom of interrupter 32 is then connected through the blast valvehousing 29 to the bottom of interrupter 33. The top of interrupter 33 isin turn connected to the stud 39 of bushing 14 by flexible connectors,such as flexible connectors 40 and 41. The connection previouslyreferred to between interrupter 30 and stud 35 incorporates flexibleconnectors, such as the connectors 40 and 41. The connection to stud 39is then covered by the corona shield 42.

FIG. I also shows voltage distributing impedances 43 and 44 connectedacross interrupters 30 and 33, respectivelyv Note that any suitablearrangement of parallel-connected capacitors or resistors could be usedacross the various interrupters 30 to 33 in order to assure appropriatedistribution of steady state and transient voltages across theseries-connected breaks.

FIG. 1 illustrates the provision of transient recovery voltagecapacitors 50 and 51 which are to be connected from either of the linesides of the breaker to ground. It will be noted that the flattenedelliptical shape of tank makes available free space in the outer centralregions of the tank so that these capacitors can be mounted within thisspace without interference with the operation of the breaker or withoutinterference with the dielectric integrity of the breaker. The mount ingof these capacitors is the subject of copending application Ser. No.398,869.

It will be noted from FIG. 1 that the upper terminals of each ofcapacitors 50 and 51 are connected by relatively rigid conductors 52 and53 to the tops of interrupters 30 and 33, respectively, and are directlyand solidly connected to the bushing studs 35 and 39, re

spectively. The bottoms of capacitors 50 and 51 are then mechanicallyand electrically connected to the tank wall 10 by the support andgrounding brackets 54 and 55, respectively.

The transient recovery voltage across the breaker is then controlled bythe capacitors 50 and 51 in the manner generally set forth in US. Pat.No. 3,383.5]9, it being noted that each of capacitors 50 and 51 may havea value of approximately 0.0025 microfarads or any other desired valueselected by the circuit designer.

The interior of the insulation reservoirs 26 and 27, which communicatewith the blast valve housings 28 and 29 and thence to the interrupters30 to 33 is at a relatively high pressure, such as 15 atmospheres of thesame dielectric gas which fills tank 10.

The major pressure source for the breaker is an elongated cylinder whichis filled with gas at high pressure and which may be covered with aheater blanket 61 to ensure that the gas temperature will always besufficiently high to maintain it in a gaseous state. A protective shroud62 covers the cylinder 60 (which may extend the full length of all ofthe phases of the breaker), with portholes such as porthole 63 beingavailable to permit maintenance of the cylinder 60 and the blanket 61. Asuitable gas control system, which need not be described to understandthe present invention, provides suitable gas conduits and gas controlsto conduct gas from the cylinder 60 through the conduit 64 which passesthrough a sealing plug 65 in tube 66 which is secured to tank 10.

The high pressure conduit 64 then extends through a T-shaped member andinto conduits 67 and 68 as generally outlined by the arrows, in FIG. 1,such that high pressure gas is admitted to the interior of insulationreservoirs 26 and 27. As will be later described, this gas is normallysealed at the blast valve housings 28 and 29 and high pressure gas isreleased through the interrupters 30 and 33 and into low pressure tank10 only when the contacts of the interrupters are operated.

A suitable mechanical operating mechanism (not shown herein) is providedto mechanically actuate crank arms, such as crank arm 70 associated withtube 26, which drive operating rods which extend through the center ofsupport tubes 26 and 27 and upwardly to blast valve housings 28 and 29.Similar crank arms will be associated with each of the otherinterrupters of each phase of the breaker. Any conventional operatingmechanism, such as a spring operated mechanism or hydraulically operatedmechanism is then connected to each of the crank arms so that all blastvalves and contacts can be simultaneously operated to either open orclose all interrupter contacts.

The specific details of one interrupter structure, such as theinterrupter 30 of FIG. 1 and a portion of the blast valve housing 28,are shown in FIG. 2. Referring now to FIG. 2, the interrupter and blastvalve are shown in cross-section and at the top of FIG. 2. As will belater described, interrupters 30 to 33 are subassembled units which canbe easily installed when the breaker is as sembled. Thus, FIG. 2 showstwo flexible shunts and 81 which have upper connectors 82 and 83 whichare appropriately bolted to the stud 35 of bushing 13, while the otherends of shunts 80 and 81 are bolted to an upper conductive adaptermember 84 of the interrupter 30. Note that the stud 35 does not serve asa mechanical support for the interrupter components.

The upper adapter 84 is bolted to a second adapter portion 85 with thetwo components 84 and 85 defining a volume 86 which leads to dischargeports such as the discharge port 87 which is positioned adjacent asimilar port 88 in the shield 36. Note the position of port 88 in FIG.1.

Additional ports are distributed around the periphery of shield 36 whichlead to similar openings defined between adapter members 84 and 85. Twofurther ports of this general type are shown in FIG. 1 for shield 42 asthe ports 89 and 9t).

The adapter member 84$ further serves to threadably receive a tubulararcing terminal 91. Note that arcing terminal 91 has an opening 910therethrough which extends upwardly so that some are venting can bedirectly vertically upward along the axis of the opening in arcingterminal 91..

The use of flexible shunts to make the connection from the top ofinterrupter 30 to the terminal bushing stud 35 is made possible sincethe entire mass of interrupter structure 30 is supported on top of theblast valve housing 28. tn prior art arrangements, such as thearrangement shown in US. Pat. No. 3,526,734, the stationary Contactstructure of the interrupter is rigidly fastened to and carried by theend of the terminal bushing. This structure required careful alignment.of the interrupter components during assembly of the breaker and duringits operation. The structure shown in FIG. 2 eliminates the need foralignment during assembly of the circuit breaker and simple flexibleshunt members 30 and 81 are used to connect the top of the preassembledinterrupter 30 to the terminal bushing stud 35. Similar advantages applyto the connection between the top of interrupter 33 of FIG. 1 and theterminal bushing stud 39.

As previously described in connection with FIG. 1 the tops ofinterrupters 31 and 32 are connected in series by the flexible shunt36a. This is to be contrasted to the prior art arrangement of US. Pat.No. 3,526,734 which required a separate support insulator extending fromthe top of the housing which would physically carry the stationarycontacts for interrupters 31 and 32. by supporting interrupters 31 and32 from the blast valve housings and 29, the separate support insulatorand the alignment problems which were caused by the separate mounting ofthe stationary contacts of these interrupter-s are eliminated.

The interrupt r 313 of HQ. 2 contains an elongated, generally tubularstationary contact member 100 which has an nppcr solid ring-shaped end101 and slots which form scgntcn tn-tract fingers, such as fingers 102and 03 in its othe end. it will be further noted that the ends ofthe gns .tcd ct'mtaci's such as segmented fincontar. ii" 1 3? terminate witharcing contact inserts which may have been formed as an insert ringwhich was brand to the tubular contact member be was slotted to form thereg fore the tubular member mcntctl finger.

The boi s hit b pass through the openings in flange 161 of stationar; Pniaci it?!) are threaded into a coni 'Hthh clamps the end side of flangeltll against adaptor member 85. Ring 110 serves as an upper support torthe insulation tube 11] which is the interrupter i"? wing tube. Tube illmay be made of any (itBSST L' tutorial, surh as an epoxy reinforcedglass tube or the iii-1: The upper end of tube 111 is suitably securedto and sealed with respect to ring as by the securing key 112 andsealing ring 113.

A set of bolt openings is formed in the inner diameter of ring 110 andthese bolt openings receive bolts, such as bolt 120, which threadablyengage ring member 121 and hold it in position. The exterior lowerportion of ring 121 is threaded and threadably receives the insulationbaffle 122 which may be of a suitable arc-resistant material such asTeflon, and serves as a guide for blast gases during the openingoperation of the interrupter, and as a means to protect or shield tube111 from the hot gases created during arc interruption. Baffle 122 alsocontains a plurality of thin, axially directed and circumferentiallyspaced fins, such as fin 123. These fins then prevent the formation of avortex in the gas blast which is guided by baffle 122.

The lower end ofinsulation tube 111 is fixed in a conductive supportring and is fixed therein and sealed thereto as by the key 131 andsealing ring 132. The ring 130 is, in turn, secured to a spider plate133 as by bolts, such as bolt 134, where the spider plate is formed of aconductive disk 1340 having radially extending web sections such assections 135 and 136 which are joined to a centrally extending hollowconductive shaft 137. The shaft 137 then slidably receives the segmentedmovable contact 138 which is slidably engaged with the outer surface ofshaft 137.

The movable contact 138 consists of a generally tubularly shaped memberhaving a solid ring-shaped end 139 which with a solid arcing ring 140,wiith the lower end of Contact 138 being segmented to form separatecontact fingers, such as fingers 141 and 142.

The segmented finger elements 138 and 142 along with other similarfingers are flexed outwardly from their normal relaxed position, and aretherefor biased inwardly and into sliding engagement with the outersurface of shaft 137. The solid upper end 139 of movable contact 138 ismovable into and out of engagement with the segmented fingers, such asfingers 102 and 103 of stationary contact 100. When the segmentedfingers 102 and 103 engage the contact 100, they are elastically flexedoutwardly to inherently provide contact pressure to form a good lowresistance contact.

It will be noted, during contact operation, that the baffle 122 willlead high pressure gas up from the annular volume which surroundsmovable contact 138 and into the baffle 122 and then between theseparating contacts 138 and 100. The gas will also flow in two directions through the are, both through the center of stationary contact100 and the opening in arc terminal 91, and through the central openingin contact 138 shown as opening 151.

The movable contact 138 is connected to an operat ing shaft 152 (whichcontains the opening 151] and the upper end of shaft 152 is providedwith a flange 153. The flange 153 is engageable with the rear surface154 of the movable Contact 138 and also receives a compression spring155. The compression spring 155 is seated at its bottom on a ledge 156of a spring retaining cylinder 157 which is threadably secured withinthe upper end of contact 138. The bottom of cylinder 157 slides withinthe interior of conductive tube 137 and slides on a seal 158 within theshaft 137. The operation of the interrupter contacts described abovewill be later described after the blast valve arrangement and support ofthe interrupter from the blast valve housing 28 is described.

As is shown in FIG. 1, the blast valve housing 28 supports bothinterrupters 30 and 31. One lateral half of the blast valve housing 28is shown in FIG. 2 insofar as it relates to the support of interrupter30. it will be noted, however, that the blast valve housing 28 issymmetric so that the same structure shown in connection withinterrupter 30 is provided on the opposite side of the center line 200in FIG. 2 for the support and operation of interrupter 31.

The insulation support member 26 of FIG. 1 is partly shown in FIG. 2 andit is seen that a metal end cap 201 is fitted over and sealed to the topof insulation tube 26. The metal cap 201 then serves as the support forthe conductive support casting 202 of the blast valve housing 26.Casting 202 is provided with a slot 203 therein for passing an arm 204which is appropriately connected to the operating shaft 152 by theadapter fitting 205.

Cap 201 further serves to support ring 210 and circumferentiallydistributed posts such as posts 211 which are welded to ring 210. Theposts 211 are then welded to a valve seat plate 212 which carries thecutoff valve ring 213 of the blast valve as will be later described. Thevalve ring 213 is then held in position by a clamp 214 which is clampedinto engagement with ring 213 by bolts such as bolt 215.

The main operating rod 220, which extends from the crank of FIG. 1 thenextends through plate 212 and clamping member 214 (in sealed relationtherewith) and is connected to radiating arms, such as arm 221 of theblast valve sleeve 222. Note that sleeve 222 also carries the operatingarm 204.

The upper end of blast valve sleeve 222 is engageable with upper blastvalve seal 230 which is clamped in position by the clamping plate 231a.The ring-shaped valve seal 230 is carried on plate 231 which isgenerally supported by a ring 232 which is an integral portion of thecasting 202.

The main blast valve sleeve 222 extends downwardly and is threadablysecured to ring-shaped member 240 which has an outwardly projectingflange 241. Flange 241 is engageable with a shoulder 242 on an auxiliarysliding sleeve 243. Note that suitable sliding seals 244 and 245 sealthese sliding surfaces against pressure loss of high pressure gas whichis in the interior of cap 201.

It is not possible generally to describe the operation of theinterrupter and blast valve of FIG. 2. With the components in theposition shown, the interrupter is closed and a current path is formedfrom terminal bushing stud 35 through the flange shunts and 81 and intothe adapter members 84 and 85 and the stationary contact 100. Thecurrent then transfers from stationary contact into the movable contact138 and the contact fingers 141 and 142 and into the conductive tube137. From the conductive shaft 137 the current passes through casting202 and then to interrupter 31 which is also supported on the blastvalve housing 28. The current then proceeds through the interrupters 31,32 and 33 in the same manner and exits at bushing 14.

While the breaker is closed, the high pressure gas from within theinsulating support tube 26 fills the volume defined by the annular opengap between the bot tom seal 213 and sleeve 243 and upwardly withinsleeve 222 and up to the valve seat 230. The interior of interrupter 30is at the relatively low pressure of the interior of tank 10, ascontrasted to the high pressure which is held at the valve seat 230.

In order to open the circuit breaker, the circuit 5 breaker operatingmechanism (not shown) is actuated to cause all of the operating rods,such as operating rod 220 to move simultaneously. The downward movementof rod 220 causes the sleeve 222 to move downwardly thereby to open theseal between the upper end of 10 sleeve 222 and the valve seat 230. Thispermits the high pressure gas within sleeve 222 to move into the chamberwhich contains spider members and 136 and upwardly through the annularchannel 150 within the insulation tube 111. Thus, the pressure withinthe annular volume 150 begins immediately to increase.

At the same time, the downward movement of sleeve 222 causes the shaft152 to move downwardly and, initially, the upper flanged end 153 ofshaft 152 will cause the spring 155 to begin to compress. Thisintroduces an increasing downward force on the seal sleeve 157 and thuson the movable contact 138 which is connected to sleeve 157. Initially,however, the contact 138 does not move since the frictional forcesbetween the segmented fingers, such as fingers 141 and 142 of themovable contact against the outer surface of shaft 137 and thefrictional force between upper contact end 139 and the segmentedcontacts of the stationary contact 100 are sufficiently high to preventcontact motion. Ultimately, 30 however, the spring force becomessufficiently high as to drive the movable contact 138 downwardly,thereby causing the separation of the contact 138 from the segmentedfingers of the stationary Contact 100 with a snap action. Note thateventually the flange 153 will 3 pick up shoulder 260 of sleeve 157 ifthe movable contact does not begin to move under the force of thecompression spring 155 alone.

As the contact tip separates from the arcing contact finger portions ofthe segmented stationary 40 contact 100, an arc is drawn between them.Substantial gas pressure has already been established within chamber andhigh pressure gas may begin to flow between the separating contacts evenprior to inception of the arc as when the contact separation is somewhat45 delayed by the lost motion connection between shaft 152 and themovable contact 138.

As the contacts 100 and 138 separate, sulfur hexafluoride or a similarinterrupting gas passes rapidly through the annular region of contactseparation with 50 a portion of the gas flowing into channel 151 andanother portion of the gas flowing upwardly and through the centralopening in arc terminal 91. The majority of the gas. however, is blastedinto the interior of tank 10 through openings in the shield 36 such asthe port 88 55 in FIG. 2.

As the contacts separate, the upper arc root will seat on the arcterminal 91 and the lower arc root will extend from the arcing tip 140.The are is quickly extin guished under the influence of the rapidlymoving sulfur hexafluoride gas.

At the time the arc is extinguished. the sleeve 222 has movedsufficiently downward so that the shoulder 261 in the outside of thesleeve 262 has picked up the lower sleeve 243 so that the sleeve 243 ismoved downwardly and into engagement with valve seat 213. This operationthen cuts off the further flow of high pressure gas from the interior ofcap 201 toward the interrupter,

thereby to conserve the high pressure gas in the reservoir.

In order to reclose the breaker. the operating rod 220 is moved upwardlyso that the contact operating rod 152 moves upwardly to reclose thecontacts. Little or no gas blast is necessary during the closingoperation. Therefore. there is a time delay in the re-opening of theblast valve. Thus, the sleeve 243 remains sealed against seal 213 untilsleeve 222 and its outwardly facing extension 241 move to a sufficientlyhigh position that extension 241 engages the shoulder 242 of sleeve 243.At this point, the lower valve seat 213 is opened so that gas can flowfor the very short time until the upper end of sleeve 222 seats againstseal 230.

An important advantage of the contact structure described above is thatthe contact structure has few parts and no separate contact biasingsprings. Thus, the contact arrangement is inexpensive and reliable.Moreover, it has been found that by arranging the contacts so that thesegmented contact fingers extend from solid tubular ends for bothcontact 100 and contact 138, a shock wave is not transmitted through themoving contact fingers 138 and 142 at the time of contact separation.Therefore, there is no bouncing of the segmented contact fingers 138 and142 on the outer surface of conductive shaft 137 so that there is noburning at this surface which burning would cause a high contactresistance.

A further advantage of the structure of FIG. 2 is that a time delaystructure is easily built into the movable contact of the segmentedcontact configuration to ensure that gas blast action has started beforethe contacts separate.

A further advantage of the contact configuration shown is that. when thecontacts open, the nozzle area for allowing rapid flow of gas fromannular region 150 is snapped open with the opening of the contacts,thereby allowing an extremely large passage for the flow of highpressure gas immediately after contact separation.

The present invention makes novel use of the relatively large diametersupport tubes 26 and 27 of FIG. 1 which serve the three functions ofproviding supports for the blast valve assemblies atop them such asblast valve assemblies 28 and 29, respectively; to provide in sulationbetween the blast valve assemblies 28 and 29 to the grounded tank; andto serve as pressure vessels to store high pressure gas which is neededfor the high pressure blast operation during the operation of the blastvalves and of the interrupter contacts.

The insulation support tubes 26 and 27 may be of any desired type andgood results have been obtained when using a fiber glass tube reinforcedwith epoxy where the tube diameter is approximately 16 inches while thewall thickness of the tube could. for example, be A inch.

Each of tubes 26 and 27 is provided with metallic end caps 201-501 andS02503, respectively. Each of the metallic end caps 201, 501, 502 and503 has the construction generally shown in connection with metallic endcap 201 and are rigidly secured to and sealed against the end of theirrespective insulation tubes 26 and 27. It will be further noted in FIG.I that the facing ends of the conductive caps 201, 501, 502 and 503 maybe covered with conductive corona rings 504 to 507. The corona ring 504has been removed in FIG. 2.

As best shown in FIG. 2, the blast valve housing 28 is mounted on thetop cap 201 with the intake of the valve being within the tube 26 sothat unrestricted flow of gas can flow from the interior of the tube 26through the opened valve sleeves when the blast valve is operated.

The bottom caps 501 and 503 are provided with suitable bolt mountingmeans to enable the direct bolt mounting of the tubes 26 and 27 on thesupport platform 21.

The insulating support tubes 26 and 27 are described herein as being themain high pressure chambers for the two-pressure breaker. That is tosay. these form the chambers from which high pressure gas will flowduring an interruption operation. A further high pressure reservoir isprovided outside of the breaker such as the tank 60 which is atextremely high pressure and serves to replenish the gas of chambers 26and 27 after each gas blast operation of the breaker.

Although this invention has been described with respect to its preferredembodiments, it should be understood that many variations andmodifications will now be obvious to those skilled in the art, and it ispreferred, therefore, that the scope of the invention be limited not bythe specific disclosure herein, but only by the appended claims.

The embodiments of the invention in which an exclusive privilege orproperty is claimed are defined as follows:

l. A dead tank circuit breaker comprising, in combination:

a generally flattened spherical metallic tank filled with a dielectricgas at relatively low pressure;

a pair of terminal bushings entering the top of said tank and extendinginto the interior of said tank;

a plurality of gas blast circuit interrupters supported within said tankand insulated from said tank and electrically connected in series withone another, and electrically connected between said pair of terminalbushings;

a support platform secured to the bottom of said tank;

a relatively high pressure supply means disposed ex ternally of saidtank;

and an interrupter support; said interrupter support comprising a hollowuniform cylindrical insulation tube of relatively thin wall thickness,and first and second spaced end caps connected to the opposite ends ofsaid insulation tube;

said insulation tube being disposed within said tank with its axisextending in a vertical direction;

said first end cap being mechanically connected to said plurality ofinterrupters; said second end cap being connected to said supportplatform, whereby said interrupters are mechanically supported from saidplatform. and are electrically insulated from said tank;

and means connecting the interior of said insulation tube to said highpressure supply, whereby said insulation tube is at a relatively highpressure; the interior volume of said insulation tube being sufficientlylarge to store relatively high pressure gas in sufficient amount for atleast one gas blast operation of said plurality of interrupters.

2. The circuit breaker of claim 1 which further includes blast valvemeans for controlling the release of relatively high pressure gas fromsaid insulation tube, and through said interrupters and into theinterior of said tank during the operation of said plurality ofinterrupters; said blast valve means being mounted on said first end capmeans and communicating with the interior of said insulation tube; saidplurality of interrupters being mounted on said blast valve means.

3. The circuit breaker of claim 1 wherein said insulation tube is offiber glass construction and has a diameter of about 16 inches.

4. The circuit breaker of claim I wherein said first and second end capsare of metal.

5. The circuit breaker of claim 3 wherein said first and second end capsare of metal and wherein said end caps have cylindrical walls whichextend over the ends and outer surfaces of said insulation tube; andfirst and second corona rings surrounding the ends of said cylindricalwalls of said first and second end caps respectively.

6. The circuit breaker of claim 5 which further includes blast valvemeans for controlling the release of relatively high pressure gas fromsaid insulation tube, and through said interrupters and into theinterior of said tank during the operation of said plurality ofinterrupters; said blast valve means being mounted on said first end capmeans and communicating with the interior of said insulation tube; saidplurality ofinterrupters being mounted on said blast valve means.

7. The circuit breaker of claim 2 which further in cludes a secondinterrupter support. a second blast valve and a second plurality ofinterrupters disposed within said tank and being laterally spaced fromand parallel to said first mentioned interrupter support. blast valveand plurality of interrupters and being identically constructed thereto.said plurality of interrupters. and said second plurality ofinterrupters being series-connected between said pair of terminalbushings.

8. The circuit breaker of claim 7 wherein said insulation tube is offiber glass construction and has a diameter of about 16 inches.

9. The circuit breaker of claim 8 wherein said first and second end capsare of metal.

10. The circuit breaker of claim 8 wherein said first and second endcaps are of metal and wherein said end caps have cylindrical walls whichextend over the ends and outer surface of said insulation tube; andfirst and second corona rings surrounding the ends of said cylindricalwalls of said first and second end caps respec

1. A dead tank circuit breaker comprising, in combination: a generallyflattened spherical metallic tank filled with a dielectric gas atrelatively low pressure; a pair of terminal bushings entering the top ofsaid tank and extending into the interior of said tank; a plurality ofgas blast circuit interrupters supported within said tank and insulatedfrom said tank and electrically connected in series with one another,and electrically connected between said pair of terminal bushings; asupport platform secured to the bottom of said tank; a relatively highpressure supply means disposed externally of said tank; and aninterrupter support; said interrupter support comprising a hollowuniform cylindrical insulation tube of relatively thin wall thickness,and first and second spaced end caps connected to the opposite ends ofsaid insulation tube; said insulation tube being disposed within saidtank with its axis extending in a vertical direction; said first end capbeing mechanically connected to said plurality of interrupters; saidsecond end cap being connected to said support platform, whereby saidinterrupters are mechanically supported from said platform, and areelectrically insulated from said tank; and means connecting the interiorof said insulation tube to said high pressure supply, whereby saidinsulation tube is at a relatively high pressure; the interior volume ofsaid insulation tube being sufficiently large to store relatively highpressure gas in sufficient amount for at least one gas blast operationof said plurality of interrupters.
 2. The circuit breaker of claim 1which further includes blast valve means for controlling the release ofrelatively high pressure gas from said insulation tube, and through saidinterrupters and into the interior of said tank during the operation ofsaid plurality of interrupters; said blast valve means being mounted onsaid first end cap means and communicating with the interior of saidinsulation tube; said plurality of interrupters being mounted on saidblast valve means.
 3. The circuit breaker of claim 1 wherein saidinsulation tube is of fiber glass construction and has a diameter ofabout 16 inches.
 4. The circuit breaker of claim 1 wherein said firstand second end caps are of metal.
 5. The circuit breaker of claim 3wherein said first and second end caps are of metal and wherein said endcaps have cylindrical walls which extend over the ends and outersurfaces of said insulation tube; and first and second corona ringssurrounding the ends of said cylindrical walls of said first and secondend caps respectively.
 6. The circuit breaker of claim 5 which furtherincludes blast valve means for controlling the release of relativelyhigh pressure gas from said insulation tube, and through saidinterrupters and into the interior of said tank during the operation ofsaid plurality of interrupters; said blast valve means being mounted onsaid first end cap means and communicating with the interior of saidinsulation tube; said plurality of interrupters being mounted on saidblast valve means.
 7. The circuit breaker of claim 2 which furtherincludes a second interrupter support, a second blast valve and a secondplurality of interrupters disposed within said tank and being laterallyspaced from and parallel to said first mentioned interrupter support,blast valve and plurality of interrupters and being identicallyconstructed thereto, said plurality of interrupters, and said secondplurality of interrupters being series-connected between said pair ofterminal bushings.
 8. The circuit breaker of claim 7 wherein saidinsulation tube is of fiber glass construction and has a diameter ofabout 16 inches.
 9. The circuit breaker of claim 8 wherein said firstand second end caps are of metal.
 10. The circuit breaker of claim 8wherein said first and second end caps are of metal and wherein said endcaps have cylindrical walls which extend over the ends and outer surfaceof said insulation tube; and first and second corona rings surroundingthe ends of said cylindrical walls of said first and second end capsrespectively.